Ethanol decreases the tetraethylammonium-induced blockade of potassium channels in molluscan neurons.
A high threshold K+ current was recorded in isolated neurons of land snail using the two-microelectrode voltage clamp method. The K+ current consisted mainly of two components, the slow Ca(2+)-dependent K+ current (IK(Ca)) and a faster Ca(2+)-independent K+ current (IK(V)), the ratio of which varied from cell to cell. The action of ethanol on the blocking effects of K+ antagonists was studied. The following K+ antagonists were used: tetraethylammonium (TEA), 4-aminopyridine (4-AP) and quinine. Ethanol (2-200 mM) either produced no effect on the total K+ current or inhibited it by 6-20%. When applied in the presence of 4-AP or quinine, ethanol did not affect the blocking effect of these antagonists on K+ current, while the blocking effect of 0.1-5 mM TEA on both IK(Ca) and IK(V) rapidly (1-2 min) decreased after the application of 2-200 mM ethanol (n = 10/14). The modulating effect of ethanol was either transient or persistent in different cells. The effect persisted when the concentration of TEA was increased, thus suggesting a noncompetitive character of interaction between TEA and ethanol.
Solntseva
E I
EI
Institute of Brain Research, Russian Academy of Medical Sciences, Moscow, Russia. elena@synaptology.msk.su
Bukhanova
J V
JV
D015761:4-Aminopyridine / Q000494:pharmacology; D000818:Animals; D000431:Ethanol / Q000494:pharmacology*; D015640:Ion Channel Gating / Q000187:drug effects; D009474:Neurons / Q000502:physiology*; D018408:Patch-Clamp Techniques; D026902:Potassium Channel Blockers; D015221:Potassium Channels / Q000187:drug effects* / Q000502:physiology; D011803:Quinine / Q000494:pharmacology; D012908:Snails; D019789:Tetraethylammonium / Q000494:pharmacology*
D026902:Potassium Channel Blockers; D015221:Potassium Channels; D000431:Ethanol; D019789:Tetraethylammonium; D011803:Quinine; D015761:4-Aminopyridine